U.S. patent number 8,287,799 [Application Number 11/849,451] was granted by the patent office on 2012-10-16 for process for the production of a fuel tank and a fuel tank.
This patent grant is currently assigned to Kautex Textron GmbH & Co. KG. Invention is credited to Matthias Borchert, Dirk Eulitz, Timo Kramer, Harald Lorenz, Gerd Wolter.
United States Patent |
8,287,799 |
Borchert , et al. |
October 16, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Process for the production of a fuel tank and a fuel tank
Abstract
The invention concerns a process for the production of a
container, in particular a fuel tank of thermoplastic material, by
extrusion blow molding, wherein during shaping of the container
within a multi-part tool the container is provided with at least
one connecting element passing through the wall thereof, wherein
with at least a part of the connecting element as a lost shaping
male die the wall of the container is displaced from one side into
a tool placed on the oppositely side of the container wall and
removed. The invention further concerns a fuel tank with at least
one connecting element which is connected to the tank wall at least
in region-wise manner by intimate joining of the materials
involved.
Inventors: |
Borchert; Matthias (Bonn,
DE), Wolter; Gerd (Konigswinter, DE),
Lorenz; Harald (Bad Neuenahr-Ahrweiler, DE), Eulitz;
Dirk (Bonn, DE), Kramer; Timo (Hirz-Maulsbach,
DE) |
Assignee: |
Kautex Textron GmbH & Co.
KG (Bonn, DE)
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Family
ID: |
38812070 |
Appl.
No.: |
11/849,451 |
Filed: |
September 4, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080078761 A1 |
Apr 3, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60824486 |
Sep 5, 2006 |
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Foreign Application Priority Data
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Sep 4, 2006 [DE] |
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10 2006 041 837 |
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Current U.S.
Class: |
264/545;
264/250 |
Current CPC
Class: |
B29C
49/54 (20130101); B60K 15/03177 (20130101); B29C
49/20 (20130101); B29C 49/4802 (20130101); B65D
90/0006 (20130101); B29C 2049/2047 (20130101); B29C
2791/006 (20130101); B29C 49/04 (20130101); B29C
2049/2017 (20130101); B60K 2015/03032 (20130101); B29C
2791/007 (20130101); B29C 49/0047 (20130101); B29L
2031/7172 (20130101); B29C 2049/2008 (20130101); B29C
2049/0057 (20130101); B60K 2015/03453 (20130101); B29C
51/267 (20130101); B29C 2793/0018 (20130101) |
Current International
Class: |
B29C
43/02 (20060101) |
Field of
Search: |
;264/545,250 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10237187 |
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Jul 2003 |
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DE |
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1211196 |
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Jun 2002 |
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EP |
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1211196 |
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Jun 2002 |
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EP |
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02070421 |
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Mar 1990 |
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JP |
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02113919 |
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Apr 1990 |
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JP |
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06285963 |
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Oct 1994 |
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JP |
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2006008308 |
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Jan 2006 |
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WO |
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Primary Examiner: Johnson; Christina
Assistant Examiner: Hauth; Galen
Attorney, Agent or Firm: Grossman, Tucker, Perreault &
Pfleger, PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application
60/824,486 filed Sep. 5, 2006.
Claims
What is claimed is:
1. A process for the production of a container, comprising: shaping
the container of thermoplastic material by extrusion blow molding
within a first multi-part tool, wherein during shaping the
container is provided with at least one connecting element passing
through a wall thereof, wherein with at least a part of the
connecting element as a lost shaping male die, the wall of the
container is displaced and transformed from one side of the wall
into a second tool placed on an oppositely disposed side of the
container wall, and wherein the wall of the container is pierced
with the connecting element; and wherein the wall of the container
displaced and transformed from one side of the wall into the second
tool is transformed by the connecting element and the second tool
into an outwardly displaced portion which remains part of the wall;
and wherein the container includes a passage within the connecting
element which passes through the wall of the container when the
wall of the container is pierced with the connecting element.
2. The process as set forth in claim 1 characterised in that the
wall of the container transformed from one side of the wall into
the second tool into an outwardly displaced portion is transformed
into a peg-shaped portion.
3. The process as set forth in claim 1 characterised in that the
second tool is a multi-part tool.
4. The process as set forth in claim 1 characterised in that said
at least one connecting element comprises a configuration with a
cutting edge, or a connecting element with a needle tip.
5. The process as set forth in claim 1 characterised in that the
container is transformed from at least two preforms extruded in web
form within a three-part tool.
6. The process as set forth in claim 1 characterised in that the
connecting element is placed on an inside of the container and the
second tool is placed on an outside of the container.
Description
FIELD
The invention concerns a process for the production of a container,
in particular a fuel tank of thermoplastic material, by extrusion
blow molding.
The invention further concerns a fuel tank of thermoplastic
material.
BACKGROUND
Fuel tanks of thermoplastic materials are in principle to be
impermeable in relation to hydrocarbons. They are usually produced
from multi-layer co-extrudates which include barrier layers for
hydrocarbons. The plastic materials used for the production of
plastic fuel tanks, for example polyethylene, are in principle not
diffusion-tight in relation to hydrocarbons. In addition those
plastic materials have a tendency to swell in the presence of fuel.
For that reason the known fuel tanks of plastic material are
provided with a multi-layer wall in which an EVOH layer is embedded
as a barrier to hydrocarbons. In that respect the lack of
diffusion-tightness of the base material used does not represent a
problem.
Usually however fuel tanks are provided with installation fitments
which have air intake and venting conduits as well as electrical
connections. To produce passage means which pass through the tank
wall, it is known for the finished tank to be provided with
marked-out circles into which connecting nipples, valves or the
like are fitted. The valves, valve covers and nipples are welded to
the outside wall of the tank in such a way as to cover the
respective opening. Such connecting locations on a plastic tank
represent potential leakage points. In order to avoid leakage paths
at connections of the fuel tank it is known for connecting nipples
and valves to be produced in the form of complicated and expensive
two-component structural members, wherein generally those
structural members have at least one part comprising a plastic
material which is weldable to the tank wall, whereas functional
parts on such members usually comprise plastic materials which do
not swell in the presence of fuel. Those plastic materials (ABS,
POM) generally cannot be welded to the plastic materials used for
the tank wall.
Frequently installation fitments, valves and connecting nipples
have to be connected to the tank in a manual manufacturing stage
after the tank is finished. It is known for example for parts of
valves to be latched on the inside of the tank wall and to be
connected in positively locking relationship on the outside to
weld-on covers, weld-on nipples or the like. The complication and
expenditure involved in assembly is considerable.
A process for the production of a fuel tank of thermoplastic
material and a fuel tank with connecting elements for hoses or the
like is known from EP 1 211 196 A1. EP 1 211 196 A1 describes a
dual-shell fuel tank of thermoplastic material with a barrier layer
for hydrocarbons, which is embedded in the tank wall and whose
shell portions which are assembled to form the tank were produced
by thermoforming. In order to ensure ease of mounting connecting
elements, while maintaining a high level of permeation sealing
integrity for hydrocarbons, EP 1 211 196 A1 proposes a two-part
connecting element or a two-part fitting which includes at least an
outer portion and an inner portion, wherein the outer portion is
welded to the outside wall of the container and the inner portion
at least partially passes through the outer portion, with
displacement of the container wall and intermediate positioning
thereof. That arrangement has the advantage that the container wall
is enclosed and displaced between the component parts in such a way
that the displaced material serves as a sealing means for the
passage assembly passing through the tank wall.
Such a passage means passing through the tank wall can be
comparatively easily produced when thermoforming the half-shell
portions of the tank, but in contrast such a connection is more
difficult to implement when producing the fuel tank by extrusion
blow molding.
Therefore the object of the invention is to provide a process for
producing a container, in particular a fuel tank of thermoplastic
material, with which it is possible to provide connecting elements
thereon during the production of the container, with means of the
utmost simplicity. In that respect the invention seeks to provide
that leakage paths for hydrocarbons in the wall of the container
are as far as possible to be avoided or restricted to a
minimum.
SUMMARY
In accordance with the invention there is provided a process for
the production of a container, in particular a fuel tank of
thermoplastic material, by extrusion blow molding, wherein during
shaping of the container within a multi-part tool the container is
provided with at least one connecting element passing through the
wall thereof, wherein with at least a part of the connecting
element as a lost shaping male die the wall of the container is
displaced and transformed from one side into a mold portion placed
on the oppositely disposed side of the container wall and wherein
the wall of the container is pierced with the connecting
element.
The process according to the invention has the advantage that the
connecting element or elements in production of the container are
joined to the container while still in the first heat, that is to
say while the plastic material is still in the originally
plasticised condition. The process steps of circling out openings
or cutting off lost blowing heads and welding on attachment
fitments by means of friction welding, welding with heat reflectors
or the like are eliminated. Damage to the container wall by the
connecting element passing therethrough is restricted to a minimum.
The connecting element itself is used as a means for piercing the
container wall and remains as a lost shaping male die in the
container wall. The tool serves in that respect as a female die or
receiving means or a support means for the part of the connecting
element, which presses through the wall of the fuel tank.
In a preferred variant of the invention the wall of the container
is transformed in the tool into a peg-shaped, preferably profiled
outwardly displaced portion or protuberance.
Desirably the tool used is a multi-part tool, preferably a tool
with a slider. The use of a tool with a slider presents itself in
particular when the outwardly displaced portion or protuberance of
the container wall, which is produced by the connecting portion, is
to form a profiled contour which then can be removed from the mold
only by means of such a tool.
For that purpose the connecting element can be provided with a
peripherally extending cutting edge or with a spindle with a needle
tip.
In the process according to the invention it can be provided that
the container is transformed from at least two preforms extruded in
web form in a multi-stage mode within a three-part tool.
In that case it is advantageous if the connecting element is placed
on the inside of the container and the associated mold portion is
placed on the outside of the container.
Furthermore to attain the above-specified object there is provided
a fuel tank of thermoplastic material comprising at least one
connecting element which is connected to the tank wall at least in
region-wise manner with intimate joining of the materials involved,
for connection to lines which pass out of or into the tank, wherein
the connecting element is in the form of a lost shaping portion
which passes at one side through the container wall and which
displaces it outwardly, the outwardly displaced portion forms a
fitment portion in one piece with the tank wall for a line or a
line connection and the connecting element is provided with means
for piercing the tank wall.
The connecting element can be in the form of a conical or
cylindrical fitting, the peripheral surface of which is provided
with what is referred to as a `Christmas tree profile`.
In addition the connecting element can have an extension for
piercing the tank wall. The extension of the connecting element can
be of a spindle-like or cannula-like configuration with a
peripherally extending cutting edge or can be provided with a
needle tip.
DESCRIPTION OF THE DRAWINGS
The invention is described hereinafter by means of an embodiment by
way of example illustrated in the drawings in which:
FIG. 1 shows a diagrammatic view of the arrangement of the parts
necessary for carrying out the process in the region of the
container wall,
FIG. 2 shows a diagrammatic view of the step of passing the
connecting element through the container wall, the wall of the
container being pierced with the connecting element,
FIGS. 3 and 4 show removal of the tool in the form of a slider tool
from the container wall and removal of the outwardly displaced
portion from the mold, and
FIGS. 5 through 13 each show respective diagrammatic views
representing the operating procedure of shaping the container in
the various stages.
In FIG. 1 reference 1 denotes a portion of the preform of the fuel
tank to be produced. In the illustrated portion or region the
preform 1 forms the wall 19 of the container 10 which is still to
be finished. FIG. 13 illustrates an exemplary container 10
including a wall 19.
As shown in FIGS. 1-4, arranged on the inside (the side away from
the blow-molding tool) of the preform 1 is a gripper 2 which is
provided in the tool that is still to be described, and which as a
connecting element receives a connecting projection 3 with a line
portion 4 connected thereto. Arranged on the opposite side of the
preform 1 (the side nearest the blow-molding tool) is a multi-part
tool 5 with a slider 6 which constitutes a mold cavity 7 which
accommodates the connecting projection 3 and is of a contour which
corresponds to the later contour of the outwardly displaced portion
in the wall of the container. The tool 5 can be in the form of a
component part of the blow molding tool which is to be described in
greater detail hereinafter, but it can also be arranged separately
in the blow molding mold.
The principle of the process for applying the connecting element to
the container wall 19 can be seen from joint consideration of FIGS.
1 through 4. The gripper identified by reference 2 is pushed by way
of a manipulator or by way of a pneumatic cylinder or the like,
with the connecting projection 3 arranged in the gripper 2, into
the preform 1, in which case the preform bears against the tool 5
and the connecting projection penetrates into the mold cavity 7 of
the tool 5. In that operation the material of the preform 1 which
is still in a plastic condition is displaced with the connecting
projection 3 as a shaping male die into the mold cavity 7 and is
transformed therein. At the same time the material of the preform 1
flows around the profile of the connecting projection 3, which is
of a Christmas tree-like configuration, whereby a positively
locking connection is produced between the material of the preform
1 and the connecting projection 3 after the material has
cooled.
The connecting projection 3 is provided with a cannula 9 which has
a peripherally extending cutting edge. When the gripper 2 is
advanced the cannula 9 of the connecting projection 3 pierces
through the preform 1 so that the connecting projection 3 passes
completely through the preform 1 or the wall 19 of the finished
container 10. See FIG. 2. In that case the thermoplastic material
of the wall 19 is displaced into the mold cavity 7 and transformed
therein. After the connecting projection 3 is introduced into the
preform 1 forming the wall 19 of the container the gripper 2 is
moved back and the slider 6 is removed from the tool 5 so that the
two parts of the tool can be opened. (See FIGS. 3 and 4).
The process for the production of the container 10 can be found in
particular in FIGS. 5 through 13. Those Figures show the various
manufacturing steps in succession.
DETAILED DESCRIPTION
As already mentioned hereinbefore the container 10 is produced by
extrusion blow molding of two preforms 1 in web form. The preforms
are continuously extruded from two extrusion heads (not shown in
the drawing) with wide-slot nozzles. The extrusion heads (not
shown) are arranged above the plane of the drawing in FIGS. 5
through 13. The preforms 1 issuing therefrom are extruded between
the open parts of the blow molding tool 11 which then transforms
them into the finished container 10 in a multi-stage mode in the
procedure to be described hereinafter.
The blow molding tool 11 comprises two outer molds 12a, 12b and a
central mold 13, wherein the individual parts of the blow molding
tool 11 are mounted on mold mounting plates (not shown) which in
turn are displaceable within a closing frame assembly (not shown).
The outer molds 12a, 12b are movable away from each other to
provide an opening and closing movement of the blow molding tool
11. The central mold 13 is displaceable transversely with respect
to the opening and closing movement of the outer molds 12a,
12b.
As shown in FIG. 5 within the central mold 13 a component holder 14
is arranged on a displaceable carrier 15. The component holder 14
in turn is displaceable by means of a pneumatic cylinder 16. In a
first production step shown in FIG. 5 the outer molds 12a, 12b are
opened in relation to each other and the central mold 13 is
disposed outside the path of movement of the outer molds 12a, 12b.
In a next step in the process (see FIG. 6) the component holder is
provided with tank installation fitments which include for example
a valve with a venting line and a connecting projection 3 fixed to
the venting line.
The central mold 13 is moved between the outer molds 12a, 12b, then
the preforms 1 in web form are expelled from the extrusion heads
(not shown) and respectively cut to length between the outer molds
12a, 12b and the central mold 13. (See FIG. 6.) The outer molds
12a, 12b are closed with respect to the central mold 13. The
preforms 1 are pulled or pushed into the cavity portions 18a, 18b
of the blow molding tool 11 by means of gas pressurisation and/or
by means of an externally applied vacuum. (See FIG. 7.)
In a further step the carrier 15 moves out of the central position
in a direction towards the outer mold 12a, and the component holder
14 is extended in a direction towards the outer mold 12a by way of
the pneumatic cylinder 16. (See FIG. 8.) The connecting member
arranged on the component holder, for example the connecting
projection 3 (see FIG. 6), penetrates the preform 1 and is pushed
into the tool identified by reference 17. In that situation the
perform 1, which becomes the wall 19 of the container 10 is
displaced outwardly and transformed to constitute a peg-like
projection. The tool 17 (as illustrated by reference numeral 5 in
FIGS. 1-4) is in the form of a component part of the blow molding
tool 11 and is only diagrammatically illustrated in FIGS. 5 through
13.
The carrier 15 is then moved back into its central position again
within the central mold 13 (FIG. 9), the outer molds 12a, 12b then
open (FIG. 10), the central mold 13 is moved out from between the
outer molds 12a, 12b (FIG. 11), the outer molds 12a, 12b are closed
again, in such a way that the two intermediate products in the
cavity portions 18a, 18b are welded together (FIG. 12) to form the
finished container 10 (FIG. 13). In that last stage in the process
the container 10 can be expanded once again with the outer molds
12a, 12b in the closed condition, by gas pressurisation within the
mold cavity. That would then be effected in the usual manner with a
blowing mandrel (not shown) which is disposed between the outer
molds 12a, 12b.
Finally FIG. 13 shows removal of the finished container 10 from the
mold assembly.
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